President Donald Trump said Monday the United States is ready to build up its nuclear arsenal after announcing it is abandoning a Cold War-era nuclear treaty, as Russia warned the withdrawal could cripple global security.

Trump sparked concern globally at the weekend by saying he wanted to jettison the three-decade-old Intermediate-Range Nuclear Forces Treaty (INF) signed in 1987 by former US president Ronald Reagan and Mikhail Gorbachev, the last Soviet leader.

In explaining his decision, Trump told reporters in Washington that Russia had “not adhered to the spirit of that agreement or to the agreement itself.”

“Until people come to their senses, we will build it up,” he said, referring to America’s nuclear stockpile. “This should have been done years ago.”

“It’s a threat to whoever you want. And it includes China. And it includes Russia,” the US president continued. “And it includes anybody else who wants to play that game. You can’t do that. You can’t play that game.”

“Until they get smart, there’s going to be nobody that’s going to be even close to us.”

Russia however has warned that abandoning the agreement would be a major blow to global security.

Moscow was ready to work with the United States to salvage the agreement, the Russian Security Council said after a meeting between its chief Nikolai Patrushev and US National Security Advisor John Bolton.

Bolton, who is expected to meet Russian President Vladimir Putin Tuesday, was visiting Moscow in the wake of Trump’s announcement Saturday that he wants to do away with the pact that bans intermediate-range nuclear and conventional missiles.